To operate at optimal levels, vehicular transmissions may require that the transmission fluid be heated above, or cooled below, normal-use operating temperatures. Under high-load conditions, such as while towing significant weight, transmission fluid may become over-heated and require cooling in order to avoid adverse effects on driving conditions or durability of the transmission system itself. Under normal driving conditions, transmission fluid may need to be warmed. Warming transmission fluid reduces spin loss, which increases efficiency of the transmission and, in turn, increases overall vehicle fuel efficiency. Vehicles which are not used for heavy duty towing applications will rarely reach optimum transmission fluid temperature.